|See also simple harmonic motion a periodic motion in which the displacement is symmetrical about a point or a periodic motion that is composed of such motions|
|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
A periodic vibration, as of a violin string, in which the motions are symmetrical about a region of equilibrium. Such a vibration may have only one frequency and amplitude or may be a combination of two or more components called harmonics. Also called periodic motion.